Impacts of groundwater over exploitation on the renewal and hydrodynamic behavior of the alluvial aquifer of Sidi Bel Abbes (Algerian NW)

Abstract

Sidi Bel Abbes plain, in Western Algeria, covers an area of 813 km2 and holds an important groundwater reservoir, providing the region with a large water potential. It displays characteristics of a peri-urban aquifer, with a large agricultural sector. The climatic variations that affected this region, the development of industrial and agricultural activities along with the over-exploitation of the groundwater resource negatively impact the aquifer's hydrodynamic balance. This work is structured around a multiapproach process based mainly on geophysical data to determine the reservoir bathymetry, rainfall data, humidity data using the standardized precipitation index (SPI), piezometric maps, hydrodynamic data, and groundwater extraction rate. Results revealed a significant decrease in humidity values over time. This negatively influences the water potential of the alluvial aquifer and induces a lateral recharge from adjacent aquifers (overfilling). Indeed, the rainfall contribution to the recharge appears low compared to that of the surrounding aquifers. However, total annual rainfall above 500 mm/year may reduce the input of the adjacent aquifers. Besides, our study indicates a well-defined hydrodynamic pattern in the alluvial aquifer, due to the bowl-shaped bedrock of the aquifer and the excessive overexploitation, especially downstream (the region of Sidi Bel Abbes). Thus, this aquifer adapted to such exploitation, through continuous and systematic recharge of drainage flows by the upstream groundwater (regions characterized by a wall uplift). The aquifer’s pluviometric dependence occurs clearly in its south-western part. A 50% humidity value implies a 0–10 m increase in the water table.

Qualitative evaluation of groundwater in terms of its suitability for drinking and irrigation. The case study of Sidi-Bel-Abbes alluvial aquifer (NW Algeria)

“…Five Water samples (22.73%) are in these facies and reflect the circulation of groundwater in coarse alluvium (gravels, pebbles). In addition, it confirms the contribution of adjacent aquifers to the recharge of the alluvial aquifer, especially during low water periods when overexploitation is intense, causing an overflow condition (Otmane et al, 2021). -Sodium bicarbonate waters: represented by only one sample (4.54%) located south of Sidi-Lahcen (center of the plain).…”

Pathways for improving water governance in Western Algeria: A multi-stakeholder analysis

“…Sidi Bel Abbas city is considered one of the Algerian regions that are part of a natural area endowed with the rarest and most fragile water resources. The drinking water supply in this city suffers from a permanent deficit and an unfair allocation between the user sectors (Otmane et al, 2021). The lack of adequate institutional arrangements for water management results in challenges related to collaboration among stakeholders involved.…”